A viewpoint in The Structural Engineer (2 November 1993) gave the views of Dr Menzies as Secretary of the Standing Committee on Structural Safety (SCOSS) on ‘Improving structural safety through feedback’. Whilst I agree with the views expressed in the article, and that it is valuable to obtain feedback from engineers who have encountered failures or potential failures, I feel that there is another feedback mechanism which remains largely untapped but which could prove valuable, especially as the use of computers in design and analysis is increasing. The feedback mechanism is simply one of taking measurements of the overall characteristics of a structure when it has been constructed and comparing the measurement with the equivalent characteristic assumed in design. The parameter which should be used for the comparison is the fundamental natural frequency, and the reason for using the frequency is that it is both easy to measure and it also relates to the stiffness and mass of the structure which are two key parameters in design. I realise that engineers rarely calculate natural frequencies, but they will have all the information from their design which would allow them to do so, and this could include all the assumptions and simplifications adopted. B.R. Ellis
The process of structural analysis can involve risks, especially using computers. The paper describes a methodology for handling analysis which can help to reduce such risks and which promotes understanding of structural behaviour. Professor I.A. MacLeod
In recent years, a number of industries have adopted risk assessment as an element in their safety assurance process, in place of a purely prescriptive approach. The general approach can be used to assess various types of risk, including injury to personnel or to the environment or financial losses which have no safety implications but which may threaten business performance. A number of industries already include aspects of structural performance within risk assessments of their plant and operations; this may require only simple analysis or assumptions, but in some instances complex modelling is required. Risk assessment, howeves forms only one element in the overall safety assurance process and must be complemented by effective safety and quality management systems. M.P. Cotton and J.R. Maguire
This paper examines the direct and indirect means by which standards of structural safety are maintained. It discusses the hazards and risks to structural safety in the context of the continuing changes in the technology and management of construction and use of structures: financial risks are not addressed. J.B. Menzies
It has been apparent from the earliest days of its development that the computer would have a dramatic impact on the work of engineers. The development of the digital computer offered the potential for the manipulation of vast amounts of data and the rapid solution of mathematical equations. As early as the 1960s, commentators were suggesting that the computer would have a great technical and economic impact. Originally, the technology tended to be reserved for sophisticated analyses. Large, expensive machines needing professional support and operating in batch mode ran programs which were used only when the complexity of the job justified the trouble and expense. P.J. Gardner
Are small - and by small I mean 1-25 person-consulting practices making better use of the advantages offered by today’s computer technology and software than their big brothers? In this feature, significant recent and future developments in PC software will be explored and linked to the requirements of the structural engineer. R. Dobson